Grass Viewshed calculation

grass-viewshed.py

import grass.script as grass

grass.run_command('r.viewshed',
        input='standard.dem',
        output='viewshed',
        coordinate=[observer_x, observer_y],
        obs_elev=1.75,
        tgt_elev=0.0,
        memory=4098,
        overwrite=True,
        quiet=True
)

# mask or clip https://automating-gis-processes.github.io/CSC18/lessons/L6/clipping-raster.html
# rasterio cookbook https://mapbox.s3.amazonaws.com/playground/perrygeo/rasterio-docs/cookbook.html#generating-a-kmz-from-a-raster